1. Field of the Invention
This invention is in the field of incorporating electron gun assemblies into sealed relation within the neck of a cathode ray tube utilizing an insulating, fusible adhesive between a stem structure and a metal collar to provide mechanical rigidity and sealing between the elements.
2. Description of the Prior Art
The prior art technique for sealing an electron gun assembly into the neck of a cathode ray tube can best be described in conjunction with FIGS. 1A and 1B of the drawings. In those Figures, an electron gun 3 is shown attached to stem pins 2 which pass through and are attached to a stem 1. The stem 1 and the electron gun 3 joined to it are inserted into a neck portion 4 of a glass envelope of the cathode ray tube, and then the stem portion 1 and the portion of the neck portion 4 opposite to the same are heated and bonded by means of an oxygen burner 5 to weld or fuse the stem 1 and the neck portion 4 to each other. After fusion, a flared portion 4a of the neck portion 4 is cut away as illustrated in FIG. 1B. After the fusion, the gas within the envelope is exhausted through a tip-off tube 6 which extends through the stem portion and then the tip-off tube 6 is sealed to thereby complete the sealing of the cathode ray tube.
In this prior art sealing method, since the stem 1 and the neck portion 4 are heated and fused by means of the oxygen burner 5, the electron gun 3 is necessarily heated to a high temperature and accordingly there is the possibility that the electron gun 3 may become oxidized.
Further, during the sealing process, the removal of the flared portion 4a causes glass powder pollution, and increases the assembly time.
Moreover, in the case of a very small sized cathode ray tube such as a view finder or the like, it is practically impossible to provide a tip-off tube 6 through the stem 1 and thus it is not possible to perform the exhausting process after sealing.